In LTE (Long Term Evolution) and successor systems of LTE (referred to as, for example, “LTE-advanced,” “FRA (Future Radio Access),” “4G,” etc.), a radio communication system (referred to as, for example, “HetNet” (Heterogeneous Network)) to place one or more small cells (including pico cells, femto cells and so on) having relatively small coverages of a radius of approximately several meters to several tens of meters, within a macro cell having a relatively large coverage of a radius of approximately several hundred meters to several kilometers, is under study (see, for example, non-patent literature 1).
Given this radio communication system, a scenario to use the same frequency F1 in both the macro cell and the small cells as shown in FIG. 1A (“co-channel”), and a scenario to use mutually different frequency bands (carriers) F1 and F2 between the macro cell and the small cells as shown in FIG. 1B (“separated frequencies,” “non-co-channel,” etc.) are under study. Also, in the scenario illustrated in FIG. 1B, a study is also in progress to use different frequencies F2 and F3 between the small cells.